Comment by varenc
2 hours ago
I disagree about JIT performance not mattering. I enabled "Lockdown Mode" on iOS which disables the JIT for the mentioned security reasons, and it causes a very noticeable lagginess on many sites. Of course, the primary cause is the unnecessary JS monstrosities wasting CPU cycles. But practically speaking I can say that disabling the JIT results in a very subpar experience of many JS heavy pages.
That's largely because a lot of developers have made the devil's bargain of replacing standard web stuff with badly re-implemented JS versions of same. People did it because they could, but never considered if they should.
See most of the ecosystem around React, for reference. It's idiotic that things like URL management are done in Javascript. Or form controls. I guarantee that if we stopped doing this kind of stuff, JIT wouldn't matter.
To some extent this is just saying "developers will depend upon the performance given to them", and that's true, but it's also true that as soon as things like V8 and Node appeared, JS became ubiquitous. Pandora's container, if you will.
you are talking about the effect, not the cause.
Sites are slow because with all that excess performance they do more tracking, instead of keeping the website as-is.
Because that's the only thing business managers can come up with in that situation. It's a misaligned goal of users vs businesses.
In my opinion the "user agent" behavior of browsers is long gone, because they're not acting on behalf of their users anymore. They're acting on behalf of businesses.
It will also increase power consumption because your CPU has to do more work to run the same code.